The present invention relates to an automatic retrieval and sequencing system, and more particularly, to a magnetic tape cassette library, retrieval and sequencing system for the automatic storage, transfer, sequencing and playback of video cassettes. While the invention is described in particular with respect to such cassette systems, those skilled in the art will recognize the wider applicability of the invention described hereinafter.
Television studios broadcast regular programming formats as well as a variety of short video messages or spots during commercial breaks. For this purpose, multiple video-tape playback machines are used to play the video-tapes in the sequence desired. With respect to spot broadcasting, for example, after each commercial break, some or all of the machines must be re-loaded with new cassettes for playback later during a subsequent commercial break. This requires constant monitoring of the equipment. Not only must the operator search for and locate the desired cassettes, but the cassettes must be located for playback in the desired sequence, as well as being unloaded and stored for subsequent use.
Recent efforts have been made seeking to automate at least some of the systematic procedures required in video tape sequencing used for spot broadcasting. In addition to previously developed automated video spot players, various types of cassette or cartridge conveying mechanisms which transport cassettes between a moving carousel and video playback machines have recently been developed. Unfortunately, some of the systems are limited because they require custom cartridges, and further because the number of cassette carried by the carousels or other types of storage bins have also been limited. In some of these machines, only between fifteen to twenty-five cartridges can be carried on a moving carousel, and in other systems, up to forty video cassettes have been carried in a single column or storage bin. Some developments have even included columns of storage bins and the use of standard video cassettes, in which computer controlled mechanisms locate the cassette and transport cassettes from the storage bins to video tape playback machines.
More recent developments have included an automatic cassette handling and sequencing system which has automated the sequencing procedures to an even greater degree. Thus, as shown in U.S. Pat. No. 4,654,727, a computer controlled system includes cassettes which are loaded into storage bins, the location of a desired cassette in the bin is sensed by a bar coded reader, a cassette manipulator mechanism is activated to move the cassette from the storage bin to a video tape playback head, and the video tapes are played on a separately located machine, in the sequencing desired. The cassette manipulator mechanism is mounted internally within a circumferentially disposed array of storage bins to allow for the sensing, loading, and transport of cassettes to a video cassette playback head. Openings are provided in the circumferentially disposed array of storage bins to enable selected cassettes to be transported to the video tape playback head, as well as to allow entry and removal of inserted/removed cassettes through the access openings in the circumferentially disposed array of storage bins. While the aforementioned automatic cassette handling and sequencing systems have sought to provide automatic handling of cassettes for regular or spot broadcasting purposes without the need for an operator, there are still numerous drawbacks in the systems developed to date. These drawbacks include the speed of operation of the system to meet regular and "spot" broadcasting demands; the flexibility of the system to accommodate changes in the program format; the adaptability of the system to different to types and sizes of cassettes and video cassette playback machines; the flexibility of the system to handle the latest cassette playback machines where two different sizes of cassettes may be inserted in a random fashion; the efficiency and operation of the cassette transporting and loading/unloading operations; and various other reasons which have inhibited the wide-spread adoption and use of such systems.